| 301 | Shield Petroleum | College Sta, TX 77845 | Oil & Gas Operator | May 2025 |
| 302 | Showdown Operating, Inc. | Dallas, TX 75230 | Oil & Gas Operator | May 1996 |
| 303 | Skytop Oil & Gas | Giddings, TX 78942 | Oil & Gas Operator | May 2025 |
| 304 | SM Energy Company | Midland, TX 79707 | Oil & Gas Operator | May 2025 |
| 305 | Smith Brothers Oil & Gas, Inc. | Midland, TX 79702 | Oil & Gas Operator | May 2025 |
| 306 | Snyder Oil Corporation | Houston, TX 77024 | Oil & Gas Operator | Mar 2008 |
| 307 | Sonoble Operating, Inc. | Dallas, TX 75240 | Oil & Gas Operator | Jun 2003 |
| 308 | South Forty Energy, Inc. | Giddings, TX 78942 | Oil & Gas Operator | Oct 1993 |
| 309 | South Texas Drilling & Expl, Inc | San Antonio, TX 78217 | Oil & Gas Operator | Jan 1999 |
| 310 | Southern Bay Operating, L.L.C. | Houston, TX 77002 | Oil & Gas Operator | Jun 2013 |
| 311 | Square One Corporation | Giddings, TX 78942 | Oil & Gas Operator | Dec 2012 |
| 312 | Stanton Mineral Development Inc | Austin, TX 78759 | Oil & Gas Operator | May 2025 |
| 313 | Sto Operating Company | San Antonio, TX 78258 | Oil & Gas Operator | May 2025 |
| 314 | Stroud Energy, LTD. | Fort Worth, TX 76102 | Oil & Gas Operator | Jun 2006 |
| 315 | Stroud Oil Properties, Inc. | Fort Worth, TX 76102 | Oil & Gas Operator | May 2013 |
| 316 | Summit Exploration, L.L.C. | Tulsa, OK 74119 | Oil & Gas Operator | Mar 2008 |
| 317 | Summit Resources MGMT., LLC. | Edmond, OK 73083 | Oil & Gas Operator | May 2025 |
| 318 | Swift Energy Company | Houston, TX 77060 | Oil & Gas Operator | Mar 2021 |
| 319 | Tamarack Petroleum Company, Inc. | Midland, TX 79701 | Oil & Gas Operator | May 2025 |
| 320 | Tanglewood Oil & Gas Co. | Gouldbusk, TX 76845 | Oil & Gas Operator | May 2025 |
| 321 | Taos Resources Operating Co LLC | Houston, TX 77037 | Oil & Gas Operator | Dec 2019 |
| 322 | TDT Production, Inc. | Capitola, CA 95010 | Oil & Gas Operator | Aug 2003 |
| 323 | Tekna Synergy Corporation | Midland, TX 79702 | Oil & Gas Operator | May 2025 |
| 324 | Tex-Lee Operating Company | Giddings, TX 78942 | Oil & Gas Operator | May 2025 |
| 325 | Texakoma Oil & Gas Corp | Dallas, TX 75240 | Oil & Gas Operator | Sep 2014 |
| 326 | Texas Energy Reserves, Inc | New Braunfels, TX 78130 | Oil & Gas Operator | Jun 1996 |
| 327 | Texas Independent Explor LTD. | Houston, TX 77024 | Oil & Gas Operator | May 2025 |
| 328 | Texas Independent Explor., Inc. | Houston, TX 77002 | Oil & Gas Operator | Oct 2002 |
| 329 | Texas Oil And Gas Operating, LLC | Friendswood, TX 77546 | Oil & Gas Operator | May 2025 |
| 330 | Texas Onshore Energy, Inc. | Austin, TX 78704 | Oil & Gas Operator | May 2025 |
| 331 | Texas Vanguard Oil Company | Austin, TX 78720 | Oil & Gas Operator | Jan 2014 |
| 332 | Three Forks Operating Co, LLC | Flatonia, TX 78941 | Oil & Gas Operator | May 2025 |
| 333 | Tipperary Oil & Gas Corp | Denver, CO 80202 | Oil & Gas Operator | May 2014 |
| 334 | Tiza Operating Company | Austin, TX 78716 | Oil & Gas Operator | Jan 2000 |
| 335 | Torch Operating Company | Houston, TX 77010 | Oil & Gas Operator | Mar 2015 |
| 336 | Tracker Oil & Gas, Inc. | Bastrop, TX 78602 | Oil & Gas Operator | May 2025 |
| 337 | Tri-County Operating Company | Seguin, TX 78156 | Gas Operator | Feb 1997 |
| 338 | Trivista Operating LLC | Giddings, TX 78942 | Oil & Gas Operator | May 2025 |
| 339 | Txu Fuel Company | Dallas, TX 75201 | Oil & Gas Operator | May 2004 |
| 340 | Ty-Tex Exploration, Inc. | Tyler, TX 75711 | Oil Operator | Dec 2000 |
| 341 | U. S. Operating, Inc. | Dallas, TX 75252 | Oil & Gas Operator | May 2025 |
| 342 | Union Oil Co Of California | Midland, TX 79706 | Oil & Gas Operator | Jan 2022 |
| 343 | Union Pacific Austin Chalk Co. | Fort Worth, TX 76101 | Oil & Gas Operator | Jan 2001 |
| 344 | Union Pacific Resources Co. | Fort Worth, TX 76101 | Oil & Gas Operator | Sep 2002 |
| 345 | United Oil & Minerals L. P. | Austin, TX 78746 | Oil & Gas Operator | Jun 2003 |
| 346 | United Oil & Minerals, Inc. | Austin, TX 78746 | Oil & Gas Operator | Jan 2001 |
| 347 | Ursa Operating Company LLC | Denver, CO 80265 | Oil & Gas Operator | Dec 2020 |
| 348 | Usfg Oil & Gas, Inc. | Dallas, TX 75231 | Oil & Gas Operator | Dec 2005 |
| 349 | Valence Operating Company | Kingwood, TX 77339 | Oil & Gas Operator | May 2025 |
| 350 | Validus Operating Inc. | Port Aransas, TX 78373 | Oil & Gas Operator | Oct 1998 |
| 351 | Venado Oil & Gas, LLC | Austin, TX 78738 | Oil & Gas Operator | Oct 2016 |
| 352 | Venado Petroleum Corporation | Dallas, TX 75231 | Oil & Gas Operator | May 2012 |
| 353 | Wagner, Duer & Co. | Fort Worth, TX 76102 | Oil & Gas Operator | Jan 1999 |
| 354 | Ward Trust | Spring, TX 77383 | Oil & Gas Operator | May 2013 |
| 355 | Warren Production Services | Caldwell, TX 77836 | Oil & Gas Operator | May 2025 |
| 356 | WCS Oil & Gas Corporation | Dallas, TX 75209 | Oil & Gas Operator | Aug 2021 |
| 357 | Weber Energy Corporation | Dallas, TX 75219 | Oil & Gas Operator | Feb 2017 |
| 358 | Wehunt Oil Company, Inc. | Dallas, TX 75376 | Oil & Gas Operator | Nov 2002 |
| 359 | Westlands Resources Corporation | Monrovia, CA 91016 | Oil & Gas Operator | May 2025 |
| 360 | Whiting Oil And Gas Corporation | Houston, TX 77002 | Oil & Gas Operator | May 2025 |
| 361 | Wildfire Energy Operating LLC | Houston, TX 77224 | Oil & Gas Operator | May 2025 |
| 362 | Wildhorse Resources MNGT Co, LLC | Oklahoma City, OK 73154 | Oil & Gas Operator | May 2019 |
| 363 | Williams, Clayton Energy, Inc. | Houston, TX 77070 | Oil & Gas Operator | May 2025 |
| 364 | Williams, Clayton Energy, L.L.C | Midland, TX 79705 | Oil & Gas Operator | May 1993 |
| 365 | Williams, Clayton W., Jr., Inc. | Midland, TX 79705 | Oil & Gas Operator | Mar 2008 |
| 366 | Wilson Hydrocarbon Inc. | Houston, TX 77066 | Oil & Gas Operator | May 2025 |
| 367 | Wimco | Dallas, TX 75229 | Oil & Gas Operator | Jul 2008 |
| 368 | XTO Energy Inc. | Spring, TX 77389 | Oil & Gas Operator | May 2025 |